The 124A Audio Level Interface from Aphex is designed to allow the connection and use of consumer hi-fi equipment and electronic keyboards, with professional and industrial audio systems. It provides an extremely clean, reliable two-way buffer, so that both systems can operate at maximum performance levels, matching both impedance and operating levels.
Plugging a -10dBV level output (such as is commonly found on synthesizers or consumer hi-fi systems) into a +4dBu professional level source results in very low audio levels. The reverse is also true, except that here, the output is too hot for the unbalanced inputs. Noise and dynamic range are compromised when compensating for such a hookup by boosting or cutting signal.
The inputs and outputs of the 124A are transformerless, for wide, flat frequency response. Hum and noise rejection is very high, while distortion is almost non-existent. The unit is actively balanced and buffered in both directions, with very low output impedance. In addition, all inputs and outputs are carefully filtered to provide freedom from RF interference.